1. Field of the Invention
The present invention relates to a recording apparatus which carries out recording on a recording medium.
2. Description of the Related Art
A recording apparatus which carries out recording on a recording paper, in general, includes a plurality of recording elements, and a drive unit which drives the plurality of recording elements based on a signal from a control circuit. For instance, an ink-jet head which carries out printing on a recording medium by jetting an ink from a plurality of nozzles has hitherto been known. This ink-jet head includes a piezoelectric actuator which applies pressure for jetting ink from the plurality of nozzles, and a driver IC (drive unit) which supplies a drive signal to a plurality of individual electrodes, of the piezoelectric actuator, corresponding to the plurality of nozzles respectively.
In a certain recording apparatus, seven types of waveform signals corresponding to seven available operation modes (including a non jetting mode in which no liquid droplets are jetted), and selection data (printing data signal) each consisting of three-bit data are input to the driver IC from a control circuit board of a printer. The selection data indicates information as to which waveform signal is to be associated for each of the nozzles. The three-bit data of each of the selection data is input serially from the control circuit to the driver IC.
The driver IC includes a shift register (a serial-parallel converter), a D flip-flop (a latching circuit), a multiplexer (a waveform selector circuit), and a drive buffer. The shift register converts a plurality of selection data which has been input serially from the control circuit corresponding to the plurality of nozzles, into parallel data, and outputs to the D flip-flop. The D flip-flop holds the plurality of selection data which has been input in parallel from the shift register until a strobe signal which indicates completion of input of a block of the selection data corresponding to all the nozzles. When the strobe signal is input, the D flip-flop outputs the block of the selection data which is held in the D flip-flop to the multiplexer in parallel. The multiplexer selects one of the waveform signals among the seven types of waveform signals based on the selection data for each of the nozzles. The drive buffer generates a drive signal by amplifying the waveform signal which has been output from the multiplexer, and outputs the drive signal to the piezoelectric actuator.
Here, eight combinations (eight bit-patterns) are possible for three-bit data forming the selection data. Out of these eight combinations, seven combinations are assigned to the abovementioned seven types of operation modes, whereas, the remaining one type (concretely, ‘111’), is used for a purpose other than selecting the operation mode (waveform signal) in the driver IC.
The strobe signal may be generated by the control circuit, and may be transferred to the D flip-flop in the driver IC when the transfer of all the selection data is completed. However, in the abovementioned recording apparatus, the driver IC includes a strobe-signal generating circuit which generates the strobe signal and outputs the strobe signal to the D flip-flop.
In the abovementioned recording apparatus, out of the three-bit combinations which are input serially from the control circuit to the driver IC, one type of combination (‘111’) is not used for the selection data selecting the operation mode (waveform signal). Therefore, even though bit data ‘1’ is transferred continuously for three times or more, it is possible to distinguish certain data consisting of successive three times or more ‘1’ bits from the seven types of the selection data corresponding to the seven types the waveform signals. Therefore, in the abovementioned recording apparatus, the control circuit is configured such that, bit ‘1’ is transferred continuously for five times at an end of the plurality of selection data, and that when the strobe-signal generating circuit in the driver IC receive the data consisting of the five successive “1” bits, the strobe-signal generating circuit judges that the input of the selection data corresponding to all the nozzles is over, and generates the strobe signal to output to the D flip-flop. In this manner, since the strobe signal is generated in the driver IC, it is possible to omit a signal wire for transmitting the strobe signal from the control circuit to the driver IC.